Based on the vehicle dynamic equation in starting engine in-motion process for HEV, theoretical derivation is conducted to obtain the impact hardness equation in the process. By using matlab/simulink, the law of influence the parameters have on the impact hardness equation is analyzed. Then, coordinated control stategy between the clutch pressure and motor torque, and between motor torque and engine torque is proposed based on the influence law. At last a test bed of the starting engine in-motion for HEV is implemented. The test results show that the change rate of clutch pressure, motor torque and engine torque, can effectively coordinate the change relation between the clutch pressure, the motor torque, and the engine torque. And the test results satisfy the requirements of ride comfort in starting engine in-motion process for HEV well.